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Homework Help: Circular momentum - Loop-the-loop question.

  1. Sep 25, 2012 #1
    1. The problem statement, all variables and given/known data

    A loop-the-loop machine has radius 18m. What is the minimum speed at which a cart must travel so that it will safely loop the loop?

    2. Relevant equations

    centripetal acceleration: v^2/r
    Perhaps more?

    3. The attempt at a solution

    To be honest, my main problem is that I'm not really sure where to start. I calculated the displacement a cart must travel, i.e. the circumference of the diameter, but I don't know what to do next..
  2. jcsd
  3. Sep 25, 2012 #2
    You want gravity to be nullified by centripetal acceleration when car is at highest point.
  4. Sep 25, 2012 #3
    Ah. You mean that when it is at the highest point, the centriputal acceleration will have the same magnitude and direction as gravity and thus, we can deduce that the centriputal acceleration is 9.8ms^-2?
  5. Sep 25, 2012 #4
    That's it.
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